strength通常指体力或人、事物等拥有的实力。
例句：
1、His energy was unbounded and his patience inexhaustible.
他有无穷的精力和无限的`耐心。
2、Plants produce sugars and starch to provide themselves with energy.
植物产生糖和淀粉来为自身提供能量。
3、Her decision to continue shows great strength of will.
她决心坚持下去，显示出了很大的意志力。